I don_t think this is going to amount to much, said Jaime Suchlicki, head of the Cuban Institute at the University of Miami. "Regardless of what President Obama said today, he needs congressional approval for making any major changes in U.S. relations with Cuba."..

I don_t think this is going to amount to much,_ said Jaime Suchlicki, head of the Cuban Institute at the University of Miami. _Regardless of what President Obama said today, he needs congressional approval for making any major changes in U.S. relations with Cuba._

Suchlicki and other experts cited four reason why the announcement in the short term might not turn out to be as significant as many in the administration believe.

First, while the 1960 U.S. embargo on Cuba has been gradually eroded over the decades and the United States has become the largest supplier of food and agricultural products to the island, the U.S. economic sanctions remain in place, and can only be lifted by Congress. Overall, American companies are still barred from buying from or selling to Cuba, or to extend credit to the island without special U.S. government permits.

In his speech Wednesday, Obama announced, among other things, plans to open a U.S. Embassy in Havana, a dramatic increase in exceptions to the travel ban on Americans wanting to visit Cuba, an expansion of commercial activities under new exceptions to the U.S. embargo and possible U.S. support for loans from multi-lateral financial institutions to Cuba. Obama, who also announced the release of U.S. subcontractor Alan Gross from Cuban prison, said the measures are _the most significant changes in our (Cuba) policy in more than 50 years._

Second, with the Republican takeover of of Congress in the Nov. 4 mid-term elections, a lifting of the embargo is highly unlikely. What_s more, there will be strong pressure from Cuban-American legislators to block Obama_s measures,the experts say.

Republican leaders such as Sen. Marco Rubio of Florida are already denouncing Obama for allegedly exceeding his presidential authority with Wednesday_s announcements of increased U.S. travel and commerce to Cuba.

Sen. Bob Menendez, D-N.J., outgoing chairman of the U.S. Senate Foreign Relations Committee and an Obama ally on key foreign policy issues, said Wednesday that when the new Congress convenes in January, he will urge incoming committee Chairman Bob Corker, R-Tenn., _to hold hearings on this dramatic and mistaken change of policy._

Third, while there has been no U.S. Embassy in Cuba since 1961, the United States has had a permanent diplomatic mission on the island ever since, known as the U.S. Interests Section in Havana. By some measures, it is already one of the largest foreign diplomatic missions on the island, and its transformation into a U.S. Embassy may only be a change in name.

_This is a game of smoke and mirrors,_ said Frank Calzon, head of the Center for a Free Cuba, about the White House_s plans for an embassy on the island. _Many people ignore the fact that there are already more American diplomats in Cuba than there are Canadian, Spanish or even Russian diplomats there._

In addition, Republicans in Congress are likely to block Obama_s nomination of a U.S. ambassador to Cuba, as they have recently done with his nominee to Argentina and other less contentious countries.

Sen. Lindsay Graham, R-S.C., who is scheduled to become chairman of the Senate Appropriations Subcommittee and handles State Department issues, posted on Twitter Wednesday that _I will do all in my power to block the use of funds to open an embassy in Cuba._

Fourth, some Cuba watchers argue that the Castro regime may sabotage the upcoming normalization talks because it needs to maintain a confrontation with the United States for domestic political reasons. Cuba has long argued that it cannot allow fundamental freedoms on the island because it is under attack from the United States, and a full normalization of U.S.-Cuban ties would seriously undermine its main argument to maintain a police state on the island, they say.

In his address to the nation announcing his agreement with Obama to swap prisoners and start normalization talks, Cuban leader Ra__l Castro appeared in full military uniform and stressed that the U.S.-Cuban confrontation is far from over.

_This does not mean that the main (thing) has been resolved,_ a stern-looking Castro said, reading from a prepared text. _The economic, commercial and financial blockade that causes enormous human and economic damages to our people must end._

In the past, especially during Fidel Castro_s years in power, Cuba often sabotaged U.S. efforts to improve bilateral relations, historians say.

After former President Jimmy Carter extended an olive branch to Cuba in the late 1970s, Castro unleashed the 1980 Mariel boatlift that resulted in a major political crisis for the Carter administration. Likewise, when former President Bill Clinton tried to improve ties with Cuba, the Castro regime in 1996 shot down two Miami-based Brothers to the Rescue planes that were helping Cuban refugees lost at sea, historians note.

But this time may be different, because Ra__l Castro may not react like his older brother, other Cuba watchers say. In addition, Cuba is facing a possible loss of Venezuela_s oil subsidies, and Ra__l Castro may be most interested in improving ties with Washington to jump-start the island_s economy.

_(U.S.) trade and financial liberalization bodes well for the Castro regime, which is facing economic strain as its largest benefactor, Venezuela, is facing a liquidity crisis and has been forced to reduce its aid to Cuba,_ says Risa Grais-Targow, a Latin American analyst with the Eurasia Group. _The government had few options but to accelerate the pace of Cuba_s opening, given its lack of access to international markets and financial institutions._